The invention relates to a ball valve assembly for use particularly in high temperature environments, and one that can be serviced even with rusted body bolts. The ball valve assembly is generally of the same type as that shown in U.S. Pat. No. 3,445,087, having a ball element rotatable by a stem extending perpendicular to the fluid conducting bore through a valve body, structure for allowing removal of the ball and seals through an opening concentric with the stem, and seat supports having spherically machined annular end portions. The ball valve as shown in U.S. Pat. No. 3,445,087 is generally suitable for valving fluids, however, the valve seats thereof are formed of polymeric materials. Polymeric materials are not generally suitable for use in high temperature environments as is contemplated according to the present invention. According to the present invention, a ball valve assembly is provided that is suitable for use in high temperature environments, yet has the excellent sealing between the ball and valve body. Additionally, according to the present invention it is desirable to be able to avoid all body drilling and tapping, since such tapped holes tend to rust in high temperature valves. Rusted and unloosenable threaded members cannot be unthreaded to allow servicing. Additionally, high temperature valves are often required with welded connections on the body, and for such valves serviceability while the body remains welded in the pipeline is necessary. Therefore, this invention includes provision for servicing while the body remains welded in place.
According to the present invention, a single annular metallic spring bellows is disposed between each seat support portion and the ball of a ball valve, each bellows having concave spherical ends, to provide a reasonably fluid-tight metal-to-metal seal with the seat support portion and the ball. The metals of the valve, ball, and bellows springs are chosen to suit the conditions. Higher temperature operation may thus be provided. Additionally, according to the present invention, ready removal of the ball and sealing means from the valve housing is provided by the provision of a circular bore in the valve housing concentric with the valve stem of the ball valve, and a flange member disposed in that circular bore and having bearing and valve stem receiving bores formed therein, the flange member having an annular portion in laterally supportive engagement with an annular portion of the valve housing. A simple metallic seal or sheet gasket provides the seal between the abutting annular portions, and readily releasable means--such as a plurality of nuts and through-bolts--hold the annular portions in abutting engagement. Alternatively, a disc and lock ring can substitute for the flange, and cap screws can be provided.
It is the primary object of the present invention to provide a ball valve assembly that is eminently suited for use in high temperature environments and is readily serviceable in-line even when the connecting bolts, etc., have rusted or otherwise become immovable. These and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.